Originally Posted by Lost Circuits
RAID Level1 mirrors or duplexes the information of any drive by storing an identical copy on a secondary drive. The advantage is full redundancy and fault tolerance, however, there is no performance increase, at least not with respect to write speed. The situation is somewhat different when it comes to reads since data can be accessed in a “zipper-like fashion” from both drives, meaning that alternating blocks of information are transferred from each drive to the controller. This does result in a performance increase, especially in the case of sequential read transfers.